1. 1
2. 2
3. 3
4. 4
5. 5
6. 6
7. 7
8. 8
9. 9
10. 10
11. 11
12. 12
13. 13
14. 14
15. 15
16. 16
17. 17
18. 18
19. 19
20. 20
21. 21
22. 22
23. 23
24. 24
25. 25
26. 26
27. 27
28. 28
29. 29
30. 30
31. 31
32. 32
33. 33
34. 34
35. 35
36. 36
37. 37
38. 38
39. 39
40. 40
41. 41
42. 42
43. 43
44. 44
45. 45
46. 46
47. 47
48. 48
49. 49
50. 50
51. 51
52. 52
53. 53
54. 54
55. 55
56. 56
57. 57
58. 58
59. 59
60. 60
61. 61
62. 62
63. 63
64. 64
65. 65
66. 66
67. 67
68. 68
69. 69
70. 70
71. 71
72. 72
73. 73
74. 74
75. 75
76. 76
77. 77
78. 78
79. 79
80. 80
81. 81
82. 82
83. 83
84. 84
85. 85
86. 86
87. 87
88. 88
89. 89
90. 90
91. 91
92. 92
93. 93
94. 94
95. 95
96. 96
97. 97
98. 98
99. 99
100. 100
101. 101
102. 102
103. 103
104. 104
105. 105
106. 106
107. 107
108. 108
109. 109
110. 110
111. 111
112. 112
113. 113
114. 114
115. 115
116. 116
117. 117
118. 118
119. 119
120. 120
121. 121
122. 122
123. 123
124. 124
125. 125
126. 126
127. 127
128. 128
129. 129
130. 130
131. 131
132. 132
133. 133
134. 134
135. 135
136. 136
137. 137
138. 138
139. 139
140. 140
141. 141
142. 142
143. 143
144. 144
145. 145
146. 146
147. 147
148. 148
149. 149
150. 150
151. 151
152. 152
153. 153
154. 154
155. 155
156. 156
157. 157
158. 158
159. 159
160. 160
161. 161
162. 162
163. 163
164. 164
165. 165
166. 166
167. 167
168. 168
169. 169
170. 170
171. 171
172. 172
173. 173

#!/usr/bin/perl

use strict;
use warnings;
use IPC::Open2;

# An example hook script to integrate Watchman
# (https://facebook.github.io/watchman/) with git to speed up detecting
# new and modified files.
#
# The hook is passed a version (currently 2) and last update token
# formatted as a string and outputs to stdout a new update token and
# all files that have been modified since the update token. Paths must
# be relative to the root of the working tree and separated by a single NUL.
#
# To enable this hook, rename this file to "query-watchman" and set
# 'git config core.fsmonitor .git/hooks/query-watchman'
#
my ($version, $last_update_token) = @ARGV;

# Uncomment for debugging
# print STDERR "$0 $version $last_update_token\n";

# Check the hook interface version
if ($version ne 2) {
	die "Unsupported query-fsmonitor hook version '$version'.\n" .
	    "Falling back to scanning...\n";
}

my $git_work_tree = get_working_dir();

my $retry = 1;

my $json_pkg;
eval {
	require JSON::XS;
	$json_pkg = "JSON::XS";
	1;
} or do {
	require JSON::PP;
	$json_pkg = "JSON::PP";
};

launch_watchman();

sub launch_watchman {
	my $o = watchman_query();
	if (is_work_tree_watched($o)) {
		output_result($o->{clock}, @{$o->{files}});
	}
}

sub output_result {
	my ($clockid, @files) = @_;

	# Uncomment for debugging watchman output
	# open (my $fh, ">", ".git/watchman-output.out");
	# binmode $fh, ":utf8";
	# print $fh "$clockid\n@files\n";
	# close $fh;

	binmode STDOUT, ":utf8";
	print $clockid;
	print "\0";
	local $, = "\0";
	print @files;
}

sub watchman_clock {
	my $response = qx/watchman clock "$git_work_tree"/;
	die "Failed to get clock id on '$git_work_tree'.\n" .
		"Falling back to scanning...\n" if $? != 0;

	return $json_pkg->new->utf8->decode($response);
}

sub watchman_query {
	my $pid = open2(\*CHLD_OUT, \*CHLD_IN, 'watchman -j --no-pretty')
	or die "open2() failed: $!\n" .
	"Falling back to scanning...\n";

	# In the query expression below we're asking for names of files that
	# changed since $last_update_token but not from the .git folder.
	#
	# To accomplish this, we're using the "since" generator to use the
	# recency index to select candidate nodes and "fields" to limit the
	# output to file names only. Then we're using the "expression" term to
	# further constrain the results.
	if (substr($last_update_token, 0, 1) eq "c") {
		$last_update_token = "\"$last_update_token\"";
	}
	my $query = <<"	END";
		["query", "$git_work_tree", {
			"since": $last_update_token,
			"fields": ["name"],
			"expression": ["not", ["dirname", ".git"]]
		}]
	END

	# Uncomment for debugging the watchman query
	# open (my $fh, ">", ".git/watchman-query.json");
	# print $fh $query;
	# close $fh;

	print CHLD_IN $query;
	close CHLD_IN;
	my $response = do {local $/; <CHLD_OUT>};

	# Uncomment for debugging the watch response
	# open ($fh, ">", ".git/watchman-response.json");
	# print $fh $response;
	# close $fh;

	die "Watchman: command returned no output.\n" .
	"Falling back to scanning...\n" if $response eq "";
	die "Watchman: command returned invalid output: $response\n" .
	"Falling back to scanning...\n" unless $response =~ /^\{/;

	return $json_pkg->new->utf8->decode($response);
}

sub is_work_tree_watched {
	my ($output) = @_;
	my $error = $output->{error};
	if ($retry > 0 and $error and $error =~ m/unable to resolve root .* directory (.*) is not watched/) {
		$retry--;
		my $response = qx/watchman watch "$git_work_tree"/;
		die "Failed to make watchman watch '$git_work_tree'.\n" .
		    "Falling back to scanning...\n" if $? != 0;
		$output = $json_pkg->new->utf8->decode($response);
		$error = $output->{error};
		die "Watchman: $error.\n" .
		"Falling back to scanning...\n" if $error;

		# Uncomment for debugging watchman output
		# open (my $fh, ">", ".git/watchman-output.out");
		# close $fh;

		# Watchman will always return all files on the first query so
		# return the fast "everything is dirty" flag to git and do the
		# Watchman query just to get it over with now so we won't pay
		# the cost in git to look up each individual file.
		my $o = watchman_clock();
		$error = $output->{error};

		die "Watchman: $error.\n" .
		"Falling back to scanning...\n" if $error;

		output_result($o->{clock}, ("/"));
		$last_update_token = $o->{clock};

		eval { launch_watchman() };
		return 0;
	}

	die "Watchman: $error.\n" .
	"Falling back to scanning...\n" if $error;

	return 1;
}

sub get_working_dir {
	my $working_dir;
	if ($^O =~ 'msys' || $^O =~ 'cygwin') {
		$working_dir = Win32::GetCwd();
		$working_dir =~ tr/\\/\//;
	} else {
		require Cwd;
		$working_dir = Cwd::cwd();
	}

	return $working_dir;
}